On a pleasant August evening on the seafront in Plymouth, Sal Aziz, a 24-year-old NHS administrator, was relaxing with his sister and discussing what to do for her birthday. Aziz, who is legally prescribed medical cannabis for anxiety and depression, inhaled some of his medicine from a vaporiser. About 10 minutes later, two police officers arrived and said they could smell cannabis. “I explained that I have a prescription for medical cannabis and showed the officer my medication,” recalls Aziz. “As soon as they opened the pot, they said that my medication is not legal.” He was handcuffed, and his sister was detained. Aziz said he panicked and “retreated in fear” before being pinned to the ground by an officer. He was then locked in a police cell for six hours. After his release, he lodged a formal complaint. Aziz is not the only medical cannabis patient to have been arrested since it was legalised in the UK in November 2018. Thousands now have private prescriptions for cannabis flower and are permitted to vaporise it in public, but among many police officers there is a lack of understanding about who can access it and where it can be consumed. Twenty-four medical cannabis users responded to a Guardian callout saying they had been approached by police who did not accept their explanations for consuming cannabis in public. While some said they found the police to be understanding, others said they had had their cannabis confiscated. Some were arrested, with a few being taken to court. Guy Coxxal, a legal advocate, said a dozen people had been taken to court over the past five years, and housing associations had threatened to evict people for consuming cannabis indoors, with police arriving at homes to issue anti-social behaviour orders. In Aziz’s case, he later told a police liaison officer over email that medical cannabis flower was legal through private clinics. The response revealed a lack of police knowledge of the law change. “Can you direct me to the legislation in relation to cannabis being legal to purchase from private clinics – all I can find at the moment is in relation to NHS prescribing,” the officer said in an email seen by the Guardian to Aziz, who began working as a medical cannabis advocate after his arrest. The officer later admitted that police had been “ill-equipped to deal with patients lawfully in possession of cannabis”. He confirmed that the Devonand Cornwall police force had consequently updated and rewritten its relevant policy and “produced a training package that is designed to help the frontline officers in being able to identify genuine medicinal cannabis patients”. Nicky Donaldson, a 33-year-old eBay trader, ended up handcuffed and taken to a police station in Glasgow after accidentally leaving his bag on a bus in October. When he went to retrieve it, he was told the driver had searched it and called the police after discovering his medical cannabis, which he was prescribed to ease his anxiety and help his recovery from alcohol use disorder. “I jumped back on the bus and as we’re driving two police officers came on board,” he recalled. “I think even the driver was a bit shocked: they put handcuffs on me there and then.” He was taken to the station and put in a cell. “The officer in charge was having none of it. He just kept saying it’s a controlled drug.” After 20 minutes in the station, Donaldson was released under investigation, with his 4g of cannabis sent for testing. Donaldson is awaiting a call from Police Scotland to tell him whether he is to be charged. Niamh Eastwood, the executive director at Release, a drug law charity, said its helpline had been receiving increasing numbers of calls from people legally prescribed cannabis who had experienced problems with the police, including being arrested for possession. “The law is clear, prescribed cannabis that is used in accordance with the instructions is legal,” she said. “The problem is the law changed but society and law enforcement has not caught up, that’s why there needs to be proactive work by the Department of Health and the Home Office to educate police, and the public, on the legal status of prescribed cannabis.” Police do sometimes accept patients’ legitimate justifications for medical cannabis possession. Ollie Taylor, then 21, woke on 16 September last year in Brighton to find police officers entering his bedroom. One of them had their hand on a holstered stun gun, having broken in through the front door. They soon realised their search warrant related to the property’s previous tenants, who had moved out weeks prior. But officers began to question Taylor, a recent university graduate, over whether he had any drugs in his room. He said he had 12g of medical cannabis, which he is prescribed for depression and anxiety. “The officer laughed and said you can only get cannabis prescribed if you’ve got cancer,” he recalled. “When I showed them a letter from my prescribing doctor, and offered to phone my clinic to confirm legitimacy, they said they didn’t have the time and left.” Sussex police said: “A small amount of cannabis found on a table was seized. Another resident disclosed to officers he had a small amount of medically prescribed cannabis. After speaking to the resident and checking prescription documentation, this cannabis was left in the possession of the resident.” On the raid it said: “Sussex police has apologised to the occupiers for the inconvenience and intrusion.” Taylor said the ordeal left him with heightened anxiety, for which he has begun taking pharmaceutical medicines for relief. Sussex police’s professional standards department rejected a complaint about the incident from Taylor, saying in an email seen by the Guardian: “I am afraid that police officers cannot be expected to know about every aspect of every law that affects UK citizens.”